Maritime Air Research Articles

Observed Variability in Convective Cell Characteristics and Near-Storm Environments across the Sea- and Bay-Breeze Fronts in Southeast Texas

Abstract During the DOE Atmospheric Radiation Measurement (ARM) Tracking Aerosol Convection Interactions Experiment (TRACER) IOP spanning June–September 2022, two fixed ARM sites and a mobile team concurrently sampled the airmass heterogeneity across sea- and bay-breeze fronts around the greater Houston metropolitan region. Here, we quantify the spatiotemporal variability between maritime (coastal/bay side of breeze fronts) and continental (inland side of breeze fronts) air masses over 15 IOP days characterized by strong sea-breeze forcing. We analyze environmental profile data from 177 radiosondes and use S- and C-band radar data to track and quantify the variability in attributes of more than 2300 shallow and transitioning cells across different air masses. The composite analysis of environmental profiles indicates that during the early afternoon, the sea-breeze maritime air mass exhibits lower convective available potential energy (CAPE) than the bay-breeze maritime air mass. As the sea breeze advances inland with time, CAPE within the maritime air mass exceeds that of the continental air mass to the north of the breeze fronts. In general, maritime cells have a larger mean composite reflectivity and cell widths than continental cells; however, the response varies between shallow and transitioning cells. Mean composite 20-dBZ echo-top heights, however, are similar across air masses for both shallow and transitioning cells. The continental and maritime inflow air mass for transitioning cells has significantly different mean values for mixed-layer entrainment CAPE, lifted condensation level, level of free condensation, boundary layer depth, and diluted equilibrium level. For shallow cells, only total precipitable water shows a significant difference. Significance Statement The greater Houston metropolitan area is a natural laboratory for understanding the individual impacts of background meteorology and aerosols on convective clouds. Due to its proximity to the Gulf Coast and Galveston Bay, the Houston region experiences a diurnal precipitation cycle in the summer, driven by convection triggered from sea- and bay-breeze fronts. These fronts act as a boundary between air masses with distinct thermodynamic and environmental characteristics. Convergence along these fronts and interactions between storm outflow and the fronts facilitate convection initiation in different mesoscale air masses. This study quantifies the heterogeneity among these air masses while investigating their influence on cloud microphysics. We find that the effect of airmass heterogeneity is more pronounced for the bulk microphysical properties in shallow clouds.

Modernisasi Alat Utama Sistem Senjata TNI dalam Mendukung Tugas TNI AL

This study analyzes the modernization of TNI AL weaponry systems to support maritime defense tasks in Indonesian jurisdictional waters. Using the Analytic Network Process (ANP) method, the research identifies the challenges and obstacles faced, as well as determining modernization priorities. The ANP results show that modernizing the Indonesian Navy Warship (KRI) is the top priority, followed by the development of Fast Missile Boats (KCR), the modernization of the Maritime Air Defense System, and the procurement of new submarines. Additionally, the Indonesian Navy faces both conventional military threats, such as naval attacks from other countries, and asymmetric threats, including piracy and maritime terrorism. To address these threats, the Indonesian Navy needs to develop advanced technologies, including cyber security and monitoring technologies to prevent illegal activities at sea. The study also finds that modernization efforts face various obstacles, requiring the improvement of maintenance facilities and intensive training. The use of ANP and NVivo helps formulate an effective modernization strategy to enhance operational readiness and the maritime defense capabilities of the Indonesian Navy.

Evening humid-heat maxima near the southern Persian/Arabian Gulf

Extreme humid heat is a major climate hazard for the coastal Arabian Peninsula. However, many of its characteristics, including diurnal and spatial variations, remain incompletely explored. Here we present evidence from multiple reanalysis and in situ datasets that evening or nighttime daily maxima in extreme wet-bulb temperature and heat index are widespread along the southern Persian/Arabian Gulf coastline and adjacent inland desert, driven principally by sea-breeze-related movements of moist maritime air. This timing runs counter to the general expectation of more intense heat and greater heat-stress risk during daytime hours. While wet-bulb temperature is one of many metrics relevant for understanding heat hazards, it has featured prominently in recent literature and its values are closer to uncompensable-heat limits in coastal Arabia than anywhere else. Deviations from an afternoon-peak assumption about heat risks are thus of critical importance and heighten the value of improved understanding of extreme-humid-heat meteorology, in this region and in others subject to similar physical processes.

An extreme precipitation event over Dronning Maud Land, East Antarctica - A case study of an atmospheric river event using the Polar WRF Model

Extreme precipitation events (EPEs) are crucial in Antarctica, impacting the Antarctic ice sheet's surface mass balance and stability. Comprehensive case studies are essential for better understanding these events and the underlying processes driving them. Here, we investigate an extreme snowfall event in Dronning Maud Land (DML), East Antarctica on November 8 and 9, 2015. This event contributed approximately 22 % of the annual accumulation in less than two days and exhibited high spatial variability in precipitation distribution. We employed a high-resolution atmospheric model specifically optimized for the polar regions (Polar WRF) and ERA5 reanalysis data to analyze the event in detail. Our findings highlight the importance of a blocking high-pressure ridge of record strength that effectively blocked and diverted a strong extratropical cyclone into DML, ultimately leading to the heavy snowfall event. The sudden deepening of the cyclone was initiated by a ‘jet streak’ in the upper atmosphere that steered the system southeastwards towards the Antarctic coast. Notably, we observed an anomalously high poleward moisture transport in the form of a strong atmospheric river on November 7, 2015. This atmospheric river originated in the South Atlantic Ocean and tracked poleward from the 30°S-40°S latitude band. Vertical cross-sections of the model outputs indicate that most of the precipitation was concentrated in regions with steep orography along the path of the atmospheric river. This interaction between the atmospheric river and the steep terrain led to the uplift of maritime air, resulting in heavy snowfall. This study highlights the significance of extreme upper and lower atmospheric conditions in driving intense moisture transport towards coastal DML. The interaction between the atmospheric river and the steep orography contributed to heavy snowfall, underscoring the importance of considering orographic influences in understanding EPEs in Antarctica.

Extreme Heat in the Caribbean: Impacts on Wellbeing and Buildings Energy Infrastructure—The 2023 Summer Case

Abstract The summer of 2023 in Puerto Rico and US Virgin Islands witnessed an unprecedented surge in extreme heat, surpassing historical norms prompting the analysis of the broader implications for the Caribbean region. This study presents the initial analysis of this remarkable heatwave, the broader context of global climate change, and its potential impacts on people's well-being and energy demand. Historical and 2023 summer daily maximum heat index (HI) are calculated using local stations and regional gridded data. The results show that summer 2023 exhibited a significant departure from the historical climate. For about 70% of summer days, HI values above 100 °F were recorded. It was found that the extreme summer is part of a broader regional pattern. The summer of 2023 recorded higher sea surface temperatures with anomalies above 2.07 °C and the weakening of the Azores High resulting in reduced wind speed in the region. This diminished the cooling effect associated with cooler maritime air aiding the stagnation of air masses over the region. The analysis sets a threshold of HI of 103 °F to assess human exposure. A significant portion of the region's population, especially in urban areas, was exposed to HI above this threshold. Concurrently, the intense heat led to increased energy demands, with about a 25% increase in peak energy demand in buildings. Per capita consumption exceeded 200 kWh/month for cooling and human comfort and anomalies adding around 15 kWh/month. The study is a step forward in developing adaptive strategies to safeguard vulnerable communities due to global warming-induced extreme events.

Estimation of Particulate Matter (PM10) Over Middle Indo-Gangetic Plain (Patna) of India: Seasonal Variation and Source Apportionment

Despite extensive research on particulate matter (PM) pollution in India’s Indo-Gangetic Plain (IGP), source apportionment remains challenging. This study investigates the effect of particulate matter (PM10)-associated water soluble inorganic ions (WSIIs) on ambient air concentration across the middle IGP from January to December 2018. Moreover, the seasonal fluctuation and chemical characterization of PM10 were assessed for the year 2018. The results revealed a high concentration of PM10 (156 µg/m3), exceeding the WHO and National Ambient Air Quality Standard (NAAQS) limits. The highest PM10 levels were observed during autumn, winter, summer, and the rainy season. The study identified SO42− and NH4+ as the most common WSIIs, constituting 46% and 23% of the total WSIIs. Source apportionment analysis indicated that street dust, biomass burning, and vehicle and industrial emissions together with secondary formation significantly contributed to IGP’s PM pollution. Additionally, the investigation of air mass back trajectory suggests that air quality in IGP is largely influenced by eastern and western Maritime air masses originated from the Arabian Sea, the Bay of Bengal, Gujarat, Afghanistan, Pakistan, and Bangladesh.

Landscape and paleoenvironmental change in stream valleys of the Central Great Plains, North America, during Marine Isotope Stage 3 (ca. 59–27 ka)

Recent studies of late Quaternary landscape evolution in stream valleys throughout the central Great Plains of North America have identified thick packages of MIS 3-age alluvium and colluvium beneath terraces, alluvial fans, and footslopes. Here, we review and build on these studies to highlight the geomorphic history of river systems in the Central Plains during MIS 3 and reconstruct the paleoclimatic conditions and vegetation communities that existed in the region at that time.A suite of 50 radiocarbon and optically stimulated luminescence ages indicate that late MIS 3 was a period of widespread landscape stability and soil development in the Central Plains. In general, river systems were actively aggrading during early MIS 3, but aggradation slowed after ca. 40 ka, allowing soils to develop until ca. 30–27 ka. In some river valleys, a second pulse of aggradation occurred shortly after that time followed by a period of landscape stability and pedogenesis during early MIS 2 (ca. 24–19 ka). Evidence for widespread landscape stability in stream valleys implies that high magnitude flooding was minimal. Atmospheric circulation patterns that favor these conditions include zonal airflow that inhibits incursions of moist, maritime air from the Gulf of Mexico.Paleoenvironmental conditions during late MIS 3 were reconstructed using the stable carbon, oxygen, and hydrogen isotopic composition of pedogenic phyllosilicates, carbonates, and organic matter. Estimated paleotemperatures ranged from 6 to 9 °C ± 3 °C and are approximately 4–7 °C lower than modern mean annual temperature. The estimated δ18O values of soil water from phyllosilicates range from −10.6‰ to −9.6‰. These estimates are lower (18O-depleted) by about 1.5–3‰ relative to modern meteoric δ18O values and we estimate that the δ18O of paleoprecipitation was likely 18O-depleted by up to 8.5‰ relative to modern values. Our estimated δ18O values for soil waters in the Central Plains during late MIS 3 can be explained by climatic conditions characterized by 1) cooler temperatures, 2) precipitation being sourced primarily from Pacific/Arctic air masses, 3) seasonal changes in precipitation patterns (i.e., predominantly winter precipitation), or 4) a combination of the above. δ13C values indicate the presence of a notable proportion of C4 vegetation in the Central Plains during late MIS 3. We suggest that C4 productivity was likely favored at that time by a low atmospheric CO2 environment that had sufficiently warm temperatures and effective precipitation during the growing season.

Precursors of summer heat waves in the Eastern Mediterranean

AbstractReanalysis and observational data are used to identify the precursors of summertime heat waves over the Eastern Mediterranean. After compiling a list of heat waves using objective criteria, we identify robust precursors present 7–10 days before the onset of the heat wave, longer than the typical horizon for trustworthy weather forecasts. If these precursors are present, there is a significant warming over the Eastern Mediterranean over the following 10 days that persists for weeks after. These precursors include a weakened Indian monsoon, a strengthened Sahelian monsoon, warm Western/Central Mediterranean sea‐surface temperatures, and a midlatitude low‐pressure system from the west. Further, horizontal temperature advection is the proximate cause of the heat wave in the days before the extreme; in particular, a weakening of the Etesian winds that would otherwise advect relatively cool maritime air inland accounts for around half of the warming. There has been a clear tendency for more heat extremes in recent years. These results have implications for forecasting anomalous summer temperatures in the Eastern Mediterranean, and the framework developed here can also be applied in other regions.

The meteorology of the 2019 North Queensland floods

AbstractIn January–February 2019, a monsoon low developed over northeastern Australia and brought extreme flooding to much of tropical Queensland. The European Centre for Medium Range Weather Forecasts reanalyses are used to explain the formation and severity of the event. Strong anticyclonic Rossby wave breaking to the southeast of Australia produced weak steering winds over northern Australia, and consequently the low remained nearly stationary for over a week, contributing to the extreme rainfall. Furthermore, the tropical moist margin was deformed by a series of disturbances along the monsoon trough, which drew moist maritime air over land. The event examined has much in common with the composite mean of slow‐moving potential vorticity anomalies in North Queensland, including weak background winds and heavy precipitation. An ensemble subseasonal forecast with the Australian Bureau of Meteorology's Australian Community Climate and Earth System Simulator Seasonal prediction version system 1 shows the same relationship between the background flow, the steering, and the subsequent rainfall. Hence, accurately forecasting the background winds is a prerequisite to forecasting such extreme rainfall.

The Variation in Atmospheric Turbidity over a Tropical Site in Nigeria and Its Relation to Climate Drivers

Atmospheric turbidity exhibits substantial spatial–temporal variability due to factors such as aerosol emissions, seasonal changes, meteorology, and air mass transport. Investigating atmospheric turbidity is crucial for climatology, meteorology, and atmospheric pollution. This study investigates the variation in atmospheric turbidity over a tropical location in Nigeria, utilizing the Ångström exponent (α), the turbidity coefficient (β), the Linke turbidity factor (TL), the Ångström turbidity coefficient (βEST), the Unsworth–Monteith turbidity coefficient (KAUM), and the Schüepp turbidity coefficient (SCH). These parameters were estimated from a six-month uninterrupted aerosol optical depth dataset (January–June 2016) and a one-year dataset (January–December 2016) of solar radiation and meteorological data. An inverse correlation (R = −0.77) was obtained between α and β, which indicates different turbidity regimes based on particle size. TL and βEST exhibit pronounced seasonality, with higher turbidity during the dry season (TL = 9.62 and βEST = 0.60) compared to the rainy season (TL = 0.48 and βEST = 0.20) from May to October. Backward trajectories and wind patterns reveal that high-turbidity months align with north-easterly air flows from the Sahara Desert, transporting dust aerosols, while low-turbidity months coincide with humid maritime air masses originating from the Gulf of Guinea. Meteorological drivers like relative humidity and water vapor pressure are linked to turbidity levels, with an inverse exponential relationship observed between normalized turbidity coefficients and normalized water vapor pressure. This analysis provides insights into how air mass origin, wind patterns, and local climate factors impact atmospheric haze, particle characteristics, and solar attenuation variability in a tropical location across seasons. The findings can contribute to environmental studies and assist in modelling interactions between climate, weather, and atmospheric optical properties in the region.

Roles of marine biota in the formation of atmospheric bioaerosols, cloud condensation nuclei, and ice-nucleating particles over the North Pacific Ocean, Bering Sea, and Arctic Ocean

Abstract. We investigated the association of marine biological indicators (polysaccharides, protein-like gel particles, and chl a) with the formation of fluorescent aerosol particles, cloud condensation nuclei (CCNs), and ice-nucleating particles (INPs) over the North Pacific Ocean, Bering Sea, and Arctic Ocean during September–November 2019. The abundance of bioindicators was high in the North Pacific Ocean and the Bering Sea (e.g., up to 1.3 mg m−3 of chl a), suggesting high biological activity due to a phytoplankton bloom. In the North Pacific Ocean, particles were characterized by high mass fractions of organics and sulfate with a predominance of terrestrial air masses. Conversely, in the Bering Sea and the Arctic Ocean, particles were characterized by high mass fractions of sea salt and sulfate with a predominance of maritime air masses. The averaged range/value of the CCN concentration at 0.4 % supersaturation were 99–151, 43–139, and 36 cm−3 over the North Pacific Ocean with terrestrial influences, over the Bering Sea with marine biogenic influences, and over the Arctic Ocean with marine influences, respectively, and the corresponding range/value of the hygroscopicity parameter κ were 0.17–0.59, 0.42–0.68, and 0.66, respectively. The averaged INP concentration (NINP) measured at temperatures of −18 and −24 ∘C with marine sources in the North Pacific and Bering Sea was 0.01–0.09 and 0.1–2.5 L−1, respectively, and that over the Arctic Ocean was 0.001–0.016 and 0.012–0.27 L−1, respectively. When marine sources were dominant, fluorescent bioaerosols in the fine mode were strongly correlated with all bioindicator types (R: 0.81–0.88) when the effect of wind-induced uplift from the sea surface to the atmosphere was considered. Correlations between NINP measured at −18 and −24 ∘C and all bioindicator types (R: 0.58–0.95 and 0.79–0.93, respectively) were positive, even when the extreme outlier point was omitted, as were those between NINP and fluorescent bioaerosols (R: 0.50 and 0.60, respectively), suggesting that marine bioindicators contributed substantially as sources of bioaerosols and to cloud formation.

A multi-scenario Lagrangian trajectory analysis to identify source regions of the Asian tropopause aerosol layer on the Indian subcontinent in August 2016

Abstract. The Asian tropopause aerosol layer (ATAL) is present during the Asian summer monsoon season affecting the radiative balance of the atmosphere. However, the source regions and transport pathways of ATAL particles are still uncertain. Here, we investigate transport pathways from different regions at the model boundary layer (MBL) to the ATAL by combining two Lagrangian transport models (CLaMS, Chemical Lagrangian Model of the Stratosphere; MPTRAC, Massive-Parallel Trajectory Calculations) with balloon-borne measurements of the ATAL performed by the Compact Optical Backscatter Aerosol Detector (COBALD) above Nainital (India) in August 2016. Trajectories are initialised at the measured location of the ATAL and calculated 90 d backwards in time to investigate the relation between the measured, daily averaged, aerosol backscatter ratio and source regions at the MBL. Different simulation scenarios are performed to find differences and robust patterns when the reanalysis data (ERA5 or ERA-Interim), the trajectory model, the vertical coordinate (kinematic and diabatic approach) or the convective parameterisation are varied. The robust finding among all scenarios is that the largest continental air mass contributions originate from the Tibetan Plateau and the Indian subcontinent (mostly the Indo-Gangetic Plain), and the largest maritime air mass contributions in Asia come from the western Pacific (e.g. related to tropical cyclones). Additionally, all simulation scenarios indicate that the transport of maritime air from the tropical western Pacific to the region of the ATAL lowers the backscatter ratio (BSR) of the ATAL, while most scenarios indicate that the transport of polluted air from the Indo-Gangetic Plain increases the BSR. While the results corroborate key findings from previous ERA-Interim-based studies, they also highlight the variability in the contributions of different MBL regions to the ATAL depending on different simulation scenarios.

Anthropogenic and Biogenic Sources Drive the Molecular Fingerprints and Atmospheric Processing of Water‐Soluble Organic Aerosols at a Tropical Hill Station in the Western Ghats of India

AbstractThe widespread presence of organic aerosols (OA) in the atmosphere and their dominant role in climate forcing are increasingly recognized. Measurements from the high‐altitude region provide insights into the natural processes and long‐range transport of aerosols. We studied water‐soluble organic compounds in PM1.1 during January‐March 2020 and February‐April 2021 at Ponmudi (8.8°N and 77.1°E), a tropical hill station (960 m a.s.l.) located on the Western Ghats of India. The 5‐day backward trajectories of air masses presented that continental and marine sources impacted the site during the campaign, and thus we classified samples as mixed and marine air masses. Their molecular fingerprints revealed the prevalence of oxalic acid (C2), followed by terephthalic acid in mixed air mass and malonic (C3) or succinic (C4) acid in maritime air mass aerosol samples. This feature and the phthalic to azelaic acid ratio, as well as the C3 to C4 and fumaric to maleic acid ratios, evidenced that water‐soluble OA were of anthropogenic origin and less photochemically aged in mixed air mass samples, whereas they derived from biogenic sources and more photochemical aging in marine air mass samples. However, we found their comparable contributions in water‐soluble organic carbon under mixed and marine air masses. Linear correlations between C2 relative abundance and its ratios with the precursor compounds implied that the oxidation of precursors to oxalic acid occurs during atmospheric transport. The results revealed that the input of anthropogenic and biogenic precursors followed by atmospheric processing controlled the burden of water‐soluble OA across the Western Ghats.

Modulation of daily PM2.5 concentrations over China in winter by large-scale circulation and climate change

Abstract. We use the United Kingdom Earth System Model, UKESM1, to investigate the influence of the winter large-scale circulation on daily concentrations of PM2.5 (particulate matter with an aerodynamic diameter of 2.5 µm or less) and their sensitivity to emissions over major populated regions of China over the period 1999–2019. We focus on the Yangtze River delta (YRD), where weak flow of cold, dry air from the north and weak inflow of maritime air are particularly conducive to air pollution. These provide favourable conditions for the accumulation of local pollution but limit the transport of air pollutants into the region from the north. Based on the dominant large-scale circulation, we construct a new index using the north–south pressure gradient and apply it to characterise PM2.5 concentrations over the region. We show that this index can effectively distinguish different levels of pollution over YRD and explain changes in PM2.5 sensitivity to emissions from local and surrounding regions. We then project future changes in PM2.5 concentrations using this index and find an increase in PM2.5 concentrations over the region due to climate change that is likely to partially offset the effect of emission control measures in the near-term future. To benefit from future emission reductions, more stringent emission controls are required to offset the effects of climate change.

Controls on Surface Warming by Winter Arctic Moist Intrusions in Idealized Large-Eddy Simulations

Abstract The main energy input to the polar regions in winter is the advection of warm, moist air from lower latitudes. This makes the polar climate sensitive to the temperature and moisture of extrapolar air. Here, we study this sensitivity from an air-mass transformation perspective. We perform simulations of an idealized maritime air mass brought into contact with sea ice employing a three-dimensional large-eddy simulation model coupled to a one-dimensional multilayer sea ice model. We study the response of cloud dynamics and surface warming during the air-mass transformation process to varying initial temperature and humidity conditions of the air mass. We find in all cases that a mixed-phase cloud is formed, initially near the surface but rising continuously with time. Surface warming of the sea ice is driven by downward longwave surface fluxes, which are largely controlled by the temperature and optical depth of the cloud. Cloud temperature, in turn, is robustly constrained by the initial dewpoint temperature of the air mass. Since dewpoint only depends on moisture, the overall result is that surface warming depends almost exclusively on initial humidity and is largely independent of initial temperature. We discuss possible climate implications of this result—in particular, for polar amplification of surface warming and the role played by atmospheric energy transports.

A System Safety Assessment (SSA) of the Maritime Air Rescue Operation of the Philippine Coast Guard (PCG)

A System Safety Assessment (SSA) of the Maritime Air Rescue Operation of the Philippine Coast Guard (PCG)

Aerosol-boundary layer dynamics and its effect on aerosol radiative forcing and atmospheric heating rate in the Indian Ocean sector of Southern Ocean

The study examines the thermodynamic structure of the marine atmospheric boundary layer (MABL) and its effect on the aerosol dynamics in the Indian Ocean sector of Southern Ocean (ISSO) between 30°S-67°S and 57°E-77°E. It includes observations of aerosols and meteorology collected during the Xth Southern Ocean Expedition conducted in December 2017. The results revealed the effect of frontal-region-specific air-sea coupling on the thermodynamic structure of MABL and its role in regulating aerosols in ISSO. The MABL over the subtropical front was unstable and formed a well-evolved mixed layer (≈2400 m) capped by low-level inversions (≈660 m). Convective activities in the Sub-Antarctic Frontal region were associated with the Agulhas Retroflection Current, which supported the formation of a well-developed mixed layer (≈1860 m). The mean estimates of aerosol optical depth (AOD) and black carbon (BC) mass concentrations were 0.095 ± 0.006 and 50 ± 14 ng m−3, respectively, and the resultant clear sky direct shortwave radiative forcing (DARF) and atmospheric heating rate (HR) were 1.32 ± 0.11 W m−2 and 0.022 ± 0.002 K day−1, respectively. In the polar front (PF) region, frequent mid-latitude cyclones led to highly stabilized MABL, supported low-level multi-layered clouds (>3-layers) and multiple high-level inversions (strength > 0.5 K m−1 > 3000 m). The clouds were mixed-phased with temperatures less than −12 °C at 3000 m altitude. Interestingly, there was higher loading of dust and BC aerosols (276 ± 24 ng m−3), maximum AOD (0.109 ± 0.009), clear sky DARF (1.73 ± 0.02 W m−2), and HR (0.029 ± 0.005 K day−1). This showed an accumulation of long-range advected anthropogenic aerosols within baroclinic-boundaries formed over the PF region. Specifically, in the region south of PF, weak convection caused weakly-unstable MABL with a single low-level inversion followed by no clouds/single-layer clouds. Predominant clean maritime air holding a small fraction of dust and BC accounted for lower estimates of AOD (0.071 ± 0.004), BC concentrations (90 ± 55 ng m−3) and associated clear sky DARF and HR were 1.16 ± 0.06 W m−2 and 0.019 ± 0.001 K day−1, respectively.

Variability of sea salt and methanesulfonate in firn cores from northern Victoria Land, Antarctica: Their links to oceanic and atmospheric condition variability in the Ross Sea

The potential ice core proxies of variability in oceanic and atmospheric conditions over the Ross Sea were evaluated. This study examined sea salt sodium (ss–Na+) and biogenic sulfur (methanesulfonate, MS–) records, covering 23 years between 1990 and 2012, from two firn cores drilled on the Styx Glacier plateau (SGP), northern Victoria Land, East Antarctica, to examine the potential links between those records and datasets for various climate variables. The comparison showed that the interannual variability of the ss–Na+ record is closely related to Pacific–South American mode 2 (PSA2) in the Ross Sea sector, exhibiting an increased ss–Na+ flux, owing most likely to more frequent penetration of maritime air masses from the western Ross Sea to the SGP when the winter/spring PSA2 mode becomes more pronounced. The observed MS– record revealed statistically significant positive correlations with the changes in the summertime chlorophyll a concentration in the Ross Sea polynya (RSP) and wind speed in the southern Ross Sea region. This indicates the dominant role of a combination of changes in the summertime primary productivity and wind speed over the RSP in modulating the MS– deposition flux at the SGP. These results highlight the suitability of the ss–Na+ and MS– records from the SGP as proxies for characterizing the dominant patterns of variability in oceanic and atmospheric conditions and their underlying mechanisms on interannual and longer timescales beyond the instrumental limits over the Ross Sea region.

Atmospheric CO2 and CH4 Fluctuations over the Continent-Sea Interface in the Yenisei River Sector of the Kara Sea

Observations of the atmospheric sources and sinks of carbon dioxide (CO2) and methane (CH4) in the pan-Arctic domain are extremely scarce, limiting our knowledge of carbon turnover in this climatically sensitive environment and the fate of the enormous carbon reservoirs conserved in the permafrost. Especially critical are the gaps in the high latitudes of Siberia, covered by the vast permafrost underlain tundra, where only several atmospheric monitoring sites are operational. This paper presents the first two years (September 2018–January 2021) of accurate continuous observations of atmospheric CO2 and CH4 dry mole fractions at the recently deployed tower-based measurement station “DIAMIS” (73.5068° N, 80.5198° E) located on the southwestern coast of the Taimyr Peninsula, Siberia, at the Gulf of the Yenisei River that opens to the Kara Sea (Arctic Ocean). In this paper, we summarized the scientific rationale of the site, examined the seasonal footprint of the station with an analysis of terrestrial vegetation and maritime sector contributing to the captured atmospheric signal, and illustrated temporal patterns of CO2 and CH4 for the daytime mixed atmospheric layer over the continent–sea interface. Along with the temporal variations reflecting a signal caused pan-Arctic and not very much influenced by the local processes, we analyzed the spatiotemporal distribution of the synoptic anomalies representing the atmospheric signatures of regional sources and sinks of CO2 and CH4 for the studied high-arctic Siberian domain of ~625 thousand km2, with nearly equal capturing the land surface (54%) and the ocean (46%) throughout the year. Both for CO2 and CH4, we have observed a sea–continent declining trend, presuming a larger depletion of trace gases in the maritime air masses compared to the continental domain. So far, over the Kara Sea, we have not detected any prominent signals of CH4 that might have indicated processes of subsea permafrost degradation and occurrence of cold seeps–still mainly observed in the eastern Arctic Seas—The Laptev Sea and the East-Siberian Sea.

PSCF and CWT methods as a tool to identify potential sources of 7Be and 210Pb aerosols in Granada, Spain

This research is focused on studying the preferred source regions and the pathways of the air masses with high particulate concentrations impacting on the activity concentrations of 7Be and 210Pb aerosols in Granada atmosphere. For this purpose, three different source-receptor methods have been used: Cluster Analysis, Potential Source Contribution Function (PSCF), and Concentration Weighted Trajectory (CWT). Air filter samples were weekly collected and analysed in Granada university (Spain 37.177N, 3.598 W, 687m a.s.l.) during 12 years (2006–2017) for the activity concentration of 7Be, and during 5 years (2010–2014) for the one of 210Pb. The time series of the collected data indicate that the concentration of both radiotracers present a cyclical and seasonal pattern, in association with their origins and atmospheric conditions. Clustering analysis showed that the air masses arriving to Granada can be classified as: (1) tropical continental air masses coming from the Mediterranean Sea, (2) tropical and warm polar maritime air masses produced over the Atlantic Ocean, and (3) continental air masses originated over Europe and Northern Africa. The PSCF and CWT methods confirmed that the main source areas of 7Be are located in the Atlantic coast of southern Morocco, and Northern Africa. On the other hand, southern France and the Algerian desert were found to be the main region sources of 210Pb. In addition, the Mediterranean Basin has been postulated as a strong source region for 7Be and 210Pb. Furthermore, the PSCF and CWT models show that the regions with larger 7Be/210Pb ratios are located in the Atlantic Ocean, due to frequent stratospheric intrusions specially during the winter months.